The present invention generally relates to the reclamation of Li for recycling and more specifically pertains to the recovery of Li from discarded batteries.
Lithium batteries are used as a reliable source of electrical energy in a wide range of applications and have been in such use for a considerable period of time. At the end of lithium battery's service life, environmental concerns and economic incentives compel the recovery and reuse of the Li contained therein. The recovery of Li is, however, problematic not only due to the instability and toxicity of the metal itself, but due to the reactivity, corrosiveness and toxicity of the various by-products and intermediate compounds that may be formed during the reclamation processes. Moreover, contamination of the Li by certain substances during the processing of the Li can render the ultimate recovery of sufficiently pure Li economically unfeasible.
A number of methods have been devised in an effort to safely and efficiently reclaim lithium from batteries. Causing the cells to be substantially discharged serves to consume most of the reactive components, thus eliminating a major portion of the hazards associated with the subsequent processing. Alternatively, or in addition thereto, cryogenically cooling the battery reduces the reactivity of the various substances to a minute fraction of their reactivity at ambient temperatures. This allows disassembly and comminution to be achieved without risk of explosion or other adverse effect. Reaction of the Li and Li compounds with H.sub.2 O causes salts to form which are safely and easily handled and which are readily sold to Li users including for example, battery manufacturers.
In reacting Li containing components to form the various salts, it is critical for a high pH to be maintained in order to avoid the formation of highly toxic H.sub.2 S. This has typically been achieved by the addition NaOH to the solution although, the concentration of Na must be strictly monitored and limited in order to avoid Na contamination in the resulting salts. Na is especially difficult to remove and inordinately high levels of Na contamination effectively render the ultimate recovery of sufficiently pure levels of Li economically unfeasible.
A method for recovering Li from batteries is therefore needed by which substantially uncontaminated Li is recovered in a safe yet more efficient manner than has heretofore been possible.